Small-cell osteosarcoma.

Six cases of small-cell osteosarcoma, a tumor that resembles Ewing's sarcoma but produces osteoid matrix, are presented. The patients were young (6-31 years of age) and presented with symptoms of pain and/or swelling of 1-10 months duration. The lesions demonstrated a wide variation in radiographic appearance. Histologically, the tumors were composed of small, round cells that produced variable amounts of osteoid. In three cases chondroid was also present. Two of the six patients were treated with surgery alone and four received radiation and either single- or multiple-agent adjuvant chemotherapy. The two patients who received radiation and multiple-agent adjuvant chemotherapy have no evidence of disease at four and ten years after diagnosis. Recognition of this tumor as distinct from Ewing's sarcoma and from other forms of osteosarcoma is important to determine the incidence, clinical features, and optimal therapy for this tumor.